title: Photo-cross-linking approach to engineering small tyrosine-containing peptide hydrogels with enhanced mechanical stability.
abstract: Peptide-based supramolecular hydrogels have been extensively explored in biomaterials owing to their unique bioactive, stimulus-responsive, and biocompatible features. However, peptide-based hydrogels often have low mechanical stability with storage moduli of 10-1000 Pa. They are susceptible to mechanical destruction and solvent erosion, greatly hindering their practical application. Here, we present a photo-cross-linking strategy to enhance the mechanical stability of a peptide-based hydrogel by 10(4)-fold with a storage modulus of ~100 kPa, which is one of the highest reported so far for hydrogels made of small peptide molecules. This method is based on the ruthenium-complex-catalyzed conversion of tyrosine to dityrosine upon light irradiation. The reinforcement of the hydrogel through photo-cross-linking can be achieved within 2 min thanks to the fast reaction kinetics. The enhancement of the mechanical stability was due to the formation of a densely entangled fibrous network of peptide dimers through a dityrosine linkage. We showed that in order to implement this method successfully, the peptide sequence should be rationally designed to avoid the cross talk between self-assembly and cross-linking. This method is convenient and versatile for the enhancement of the mechanical stability of tyrosine-containing peptide-based hydrogels. We anticipate that the photo-cross-linked supramolecular hydrogels with much improved mechanical stability will find broad applications in tissue engineering and drug controlled release.
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, and ‡National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University , 22 Hankou Road, Nanjing, Jiangsu 210093, PR China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Ding
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Meng
authors.initials: M
authors.lastname: Qin
authors.forename: Yi
authors.initials: Y
authors.lastname: Cao
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000138:chemical synthesis / Q000737:chemistry*; D020100:Hydrogels / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D010316:Particle Size; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D055668:Photochemical Processes; D015202:Protein Engineering; D013499:Surface Properties; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D020100:Hydrogels; D010455:Peptides; D014443:Tyrosine